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Fig. 1 | BMC Evolutionary Biology

Fig. 1

From: On trends and patterns in macroevolution: Williston’s law and the branchiostegal series of extant and extinct osteichthyans

Fig. 1

Skull of the Devonian actinopterygian Cheirolepis trailli in lateral (a), anterior (b), and ventral (c) view (after [59]). Opercular/ branchiostegal series in red outlines with branchiostegal rays in light red fill. The pattern of these bones in this stem-actinopterygian may be considered the basic actinopterygian pattern. The elements in this succession include the operculum, suboperculum, branchiostegal rays, and gulars. Some authors include also Dh dermohyale, aOp accessory operculum, Pop preoperculum (and other absent bones here) in the series, while others exclude the gulars from it (for references see text). Any of these elements may be missing, hence the synonymous names ‘opercular series’, ‘branchiostegal series’, ‘operculo-branchiostegal series’, and ‘operculo-gular series’. Op, operculum; Sop, suboperculum; Br, branchiostegal rays; lG, lateral gular; mG medial gular

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